Add nodiscard attribute (#10)

include/cpp-utilities/constexpr_sqrt.hpp

@@ -36,7 +36,8 @@ namespace internal {
 // Efficient square root solver. This function is a constant expression, unlike std::sqrt. This
 // function is an internal implementation detail and is not intended to be used except by the
 // utility::constexpr_sqrt function.
-inline constexpr double constexpr_sqrt_solver(const double number, const double factor) {
+[[nodiscard]] inline constexpr double constexpr_sqrt_solver(
+    const double number, const double factor) {
   // Recursively factor the input number until it falls within the [0.25, 4] interval, which greatly
   // reduces the number of Newton-Raphson iterations needed to numerically compute the square root.
   // When solving s = sqrt(x), if x can be expressed as x = n^2 * y such that y is geometrically
@@ -130,7 +131,7 @@ inline constexpr double constexpr_sqrt_solver(const double number, const double
 
 // Returns the square root of a double-precision floating-point number. This function is a constant
 // expression, unlike std::sqrt.
-inline constexpr double constexpr_sqrt(const double number) {
+[[nodiscard]] inline constexpr double constexpr_sqrt(const double number) {
   // The square root of zero is zero. Notably, the square root solver does not handle this value, so
   // it must be treated separately.
   if (number == 0.0) {